Note: As of 2016-07-05, this project appears to no longer be supported. If you are interested in taking this project over, or you as the project maintainer feel this message has been posted in error, please reply to #2747425: Automatic Nodetitles appears to be unsupported.
Be advised that there is a better maintained alternative available:
Automatic Entity Label - which also has a working D8 (beta) version

"auto_nodetitle" is a small and efficient module that allows hiding of the content title field in the form. To prevent empty content title fields one can configure it to generate the title by a given pattern.

When the token module is installed it's possible to use various node data for the
auto generated title - e.g. use the text of a CCK field (since 5.x).

Advanced users can also provide some PHP code, that is used for automatically generating an appropriate title.

Related module for Drupal 7:

Project Information